RodeoX, I think you are overestimating the computing power needed to take over the block chain, and underestimating the threat that BTC poses to the established financial community, both fiat currency providers and credit card/POS issuers.
The current hash rate is 63.686 THh/s, and a production mining rig does 50 GH/s. So with a mere 1200 commercial rigs, the entire current hash rate can be duplicated.
Do you think that these established players will let themselves be brought down when the cost is so small to bring BTC down?
BTW, I am an ASIC designer by trade, and have worked on the most powerful computers, used by Livermore Labs. I know what I'm talking about technically. It would be trivial.
It would not be trivially expensive. As in, the cost to do such an attack is not worth the the exceedingly small dent that
BTC has made in the established financial community.
Also, if they are so very established, they may believe
BTC doesn't stand a chance. It's just 1's and 0's, they may not get it.
If they are established and technically savvy, they would more likely find a way to PROFIT off of it rather than take on a HUGE expense (1200 50GH miners) just for the possibility to double-spend some bitcoins....
If they're in it for the money, they will not take a loss. But they might take as much profit as they can while making
BTC unstable and ugly to investors.